Tissue engagement devices, systems, and methods

ABSTRACT

Devices and related methods to engage tissue layers to access the space between the layers are provided. The access devices include engagement arms that can be deployed and retracted to easily engage the top tissue layer and allow it to be separated from the underlying layer. The engagement arms are coupled to an actuation rod that is in turn coupled to a switch or lever that allows a user to control the actuation from outside the patient. The engagement arms and coupling to the actuation rod are unique and compact to ensure the entire mechanism fits in a small diameter shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/002,349, titled TISSUE ENGAGEMENT DEVICES, SYSTEMS, AND METHODS,filed on Jan. 20, 2016, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 62/105,289, titledTISSUE ENGAGEMENT SYSTEM AND METHOD, filed on Jan. 20, 2015, U.S.Provisional Patent Application No. 62/221,011, titled TISSUE ENGAGEMENTSYSTEM AND METHOD, filed on Sep. 19, 2015, and U.S. Provisional PatentApplication No. 62/242,257, titled TISSUE ENGAGEMENT SYSTEM AND METHOD,filed on Oct. 15, 2015, the entire contents of each of which are herebyincorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates generally to systems, devices and methodsfor separating one tissue layer from underlying tissue or material. Morespecifically, the present disclosure relates to devices and methods foraccessing the space between a tissue layer and an underlying structure,such as the pericardial space.

BACKGROUND

In the field of cardiac medicine, minimally invasive therapies fortreating conditions at the heart's surface, or epicardium, have beendeveloped or contemplated. Example treatments include epicardialablation, left atrial appendage ligation, lead placement, and drugdelivery. An important element of these procedures is safely gainingaccess to the pericardial space through the pericardium, which is athin, protective, multi-layer membrane surrounding the heart. Asdescribed in the book Basic Human Anatomy—A Regional Study of HumanStructure by O'Rahilly et al (reference FIG. 23-1), the outermost layeris the fibrous pericardium and the inner surface facing the pericardialspace is a serous membrane called the parietal layer or pericardium.Opposing the parietal pericardium is another serous membrane called thevisceral layer, which forms the outer surface of the epicardium. Thepericardial space between the visceral and parietal layers is a thinfilm of serous fluid that provides lubrication. Because of its closeproximity to the epicardium, creating an access port through the verythin pericardium can be difficult without injuring the underlyingepicardium, heart muscles (myocardium tissue) and other structures suchas blood vessels and nerves. The movement of the beating heart,breathing motions, presence of fatty surface tissue on the externalsurface of the fibrous pericardium, and toughness of the pericardium aresome of the additional factors that can increase access difficulty.

Non-minimally invasive ways are considered surgical methods and use athorascope to create an opening in the pericardium called a pericardialwindow. Presently, the accepted minimally invasive method for accessingthe pericardial space between the pericardium and epicardium forpurposes other than draining effusions (pericardiocentesis) involvescarefully inserting a needle with fluoroscopic guidance as described bySosa E., Scanavacca M., D'Avila A., and Pilleggi F. in “A New Techniqueto Perform Epicardial Mapping in the Electrophysiology Laboratory” in JCardiovasc Electrophysiol., Vol. 7, pp. 531-536, Jun. 1996. Theprocedure today is still performed with a commercially available Tuohyneedle (typically 17G or 18G) that accommodates a standard 0.035″ guidewire. St. Jude Medical has a general Epicardial Kit that includesdifferent devices to perform epicardial procedures and a 17G Tuohyneedle for access. More recently, some epicardial access procedures arebeing performed with a 21G Micropuncture needle which, because of themuch smaller diameter, is more benign to unintended heart puncture, butvery difficult to use because it is less stiff and requires exchangingto a larger, more stable 0.035″ guide wire. Micropuncture needle kitsare commercially available from a number of different manufacturers.Using either needle type requires a high degree of skill and practice,and can be very time-consuming, and therefore this procedure has notbeen widely adopted, limiting the use of emerging epicardial therapies.Some known procedures utilize needles enhanced with electricalmeasurement capability or ultrasound to better monitor the needle tipposition during entry into the pericardial space.

It has been recognized that passing a needle through the pericardiumcould be made safer and less difficult by creating greater separationbetween the pericardium and epicardium. This has been demonstrated bythe procedure known as pericardiocentesis, a procedure for drainingexcess fluid from the pericardial space. In this situation, the excessfluid creates pressure that forces the pericardium outward allowingsafer needle passage. Various known methods to create this separationuse vacuum apparatus, adhesion, or mechanical means (such as jaws orprotruding needles). Further, some known devices for engaging tissueusing needle-like members that bend or rotate into tissue. Known devicesfor engaging tissue or for creating a greater separation between thepericardium and epicardium suffer from a variety of drawbacks, however,as will be apparent from the disclosure herein. These limitations can beameliorated or eliminated by embodiments disclosed hereafter.

SUMMARY

Certain embodiments disclosed herein include a mechanical engagementdevice that is sized to fit within a small opening such as a hypodermictube. In some implementations, the engagement device consists of one ormore small pivotable (e.g., pivotally mounted) arms with penetratingtips that engage tissue and bypass one another as they superficiallypierce into the tissue. When fully actuated, the arms are positioned insuch a way as to securely hold the tissue like hooks, allowingsubsequent tissue manipulation such as lifting, pushing, pulling, ortwisting. Lifting, for example, can create separation between the tissueand underlying layer or body of tissue beneath it. The pivotable armscan be sized and actuated to pierce into only the top layer of thetissue while minimizing the likelihood of injury or a puncture to theunderlying layer. In some instances, this mechanism can be advantageousover existing devices and techniques in its ability to selectivelyengage thin tissue. In other or further instances, the device may bemore robust to varying conditions, such as, for example, tissuethickness, toughness, and the presence of interfering tissue, such asfat.

Some embodiments advantageously facilitate passage of a needle to thearms and beyond, e.g., via a channel or conduit along a length of thedevice. The channel is located so that the needle can pierce the tissuelayer in close proximity to the arms and in a way that makesadvantageous use of the tissue traction from the tip of the engagementdevice. After the needle has passed through the tissue it may be used toperform additional procedural steps such as the introduction of a guidewire, injection of fluids such as imaging contrast agents or drugs,introduction of diagnostic or therapeutic devices, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The written disclosure herein describes illustrative embodiments thatare non-limiting and non-exhaustive. Reference is made to certain ofsuch illustrative embodiments that are depicted in the figures, inwhich:

FIG. 1 is an anterior view of the thoracic cavity of a patient.

FIG. 2 illustrates a lateral view of the thoracic cavity of the patient.

FIG. 3 illustrates a view of the chest of the patient and includesillustration of a subxiphoid approach.

FIG. 4 shows a top side perspective view of an embodiment of a tissueengagement device in an undeployed or retracted state.

FIG. 5 shows a bottom side perspective view of the tissue engagementdevice in the undeployed state.

FIG. 6 shows a cross sectional view of the tissue engagement devicetaken along the view line 6-6 in FIG. 4, or stated otherwise, takenalong a longitudinal axis of the device, that further depicts a punctureneedle inserted through the device.

FIG. 7 is an enlarged perspective view of a proximal portion of thetissue engagement device that shows a handle and a lever that ispositioned in a deployed state.

FIG. 8 shows an exploded perspective view of the portion of the tissueengagement device that is depicted in FIG. 7.

FIG. 9 shows a perspective view in partial cross-section of a tip of thetissue engagement device in the undeployed state.

FIG. 10 shows a perspective view in partial cross-section of the tip ofthe tissue engagement device in the deployed state.

FIG. 11 depicts the tip of the tissue engagement device, with portionsthereof reduced to broken lines for clarity, at various sequentialstages of deployment.

FIG. 12 shows perspective views of the same sequential stages ofdeployment of the tip of the tissue engagement device as those shown inFIG. 11.

FIG. 13A-13F depict the tip of the tissue engagement device engaging atissue layer, with the stages of deployment of each of FIGS. 13A-13Fcorresponding with the six stages of deployment depicted in each ofFIGS. 11 and 12.

FIG. 14A depicts a side view of the tissue engagement device engaging atissue layer at a shallow angle.

FIG. 14B depicts a side view of the tissue engagement device pulling thetissue layer back.

FIG. 14C depicts a side view of the tissue engagement device deploying apuncture needle through the tissue layer.

FIG. 14D depicts a side view of the puncture needle being advanced intothe pericardial space.

FIG. 14E depicts a side view of an introduction of a guide wire into thepericardial space, and the guide wire can be used to introduce otherdevices into the pericardial space.

FIGS. 15A-15D depict side views of the tip of the tissue engagementdevice at various stages of a method in which the device is used totunnel through adipose tissue on the surface of the fibrous pericardium.

FIGS. 16A is a detailed view of an embodiment of a single engagementarm.

FIG. 16B is a perspective view of the engagement arm that illustrates abevel to increase tip sharpness.

FIG. 17 shows a detailed view of another embodiment of an engagement armwith a rounded tip to reduce tissue injury.

FIG. 18 shows a detailed view of yet another embodiment of an engagementarm with teeth to enhance securement of a tissue layer.

FIG. 19 is a detailed view of the tip of a tissue puncturing needleintended to pass through the tissue layer after securement of the tissuelayer with the engagement arms of the tissue engagement device.

FIG. 20 is a perspective view of a proximal hub for a tissue puncturingneedle showing a thread feature for controlled needle advancement; theillustrated hub also has a luer fitting for attachment to a syringe.

FIG. 21 is an exploded perspective view of an embodiment of a devicehandle that incorporates a dial that engages the thread feature depictedin FIG. 20.

FIG. 22A is a detailed perspective view of a tip of another embodimentof a tissue engagement device in which a needle pathway is between theengagement arms, which are depicted in a retracted state.

FIG. 22B is a detailed perspective view of the tip of FIG. 22A thatdepicts the engagement arms in a deployed state.

FIG. 23A is a detailed perspective view of the tip of yet anotherembodiment of a tissue engagement device in which a needle pathway is onthe top of the engagement arms, which are depicted in a retracted state.

FIG. 23B is a detailed perspective view of the tip of FIG. 23A thatdepicts the engagement arms in a deployed state.

FIG. 24A is a detailed perspective view of the tip of a furtherembodiment of a tissue engagement device having engagement arms that aredepicted in a retracted state.

FIG. 24B is a detailed perspective view of the tip of FIG. 23A thatdepicts the engagement arms in a deployed state.

FIG. 25A depicts detailed sequential views of the tip of anotherembodiment of a tissue engagement device in which an actuation rod ispushed relative to a shaft to deploy the engagement arms, which arepivotally mounted to the actuation rod.

FIG. 25B depicts detailed sequential views of the tip of yet anotherembodiment of a tissue engagement device in which an actuation rod ispulled relative to a shaft to deploy the engagement arms, which arepivotally mounted to the actuation rod.

FIG. 25C depicts detailed sequential views of the tip of a still furtherembodiment of a tissue engagement device in which an actuation rod ispulled relative to a shaft to deploy the engagement arms, which arepivotally mounted to the shaft.

FIG. 26 depicts a method of using the engagement arms of a tissueengagement device to engage and manipulate tissue.

FIG. 27A is a perspective view of an embodiment of a handle for a tissueengagement device that includes an adjustable needle brake.

FIG. 27B is a cross-sectional view of the handle taken along the viewline 27B-27B in FIG. 27A.

FIG. 28A is a perspective view of another embodiment of a tissueengagement device that incorporates a threaded needle advancementmechanism and a fitting for a locking luer connection.

FIG. 28B is an obverse perspective view of the tissue engagement deviceof FIG. 28A.

FIG. 29 is a detailed perspective view of a handle portion of the tissueengagement device of FIG. 28A.

FIG. 30 is an exploded perspective view of the portion of the tissueengagement device depicted in FIG. 29.

FIG. 31 is a cross-sectional view of the tissue engagement device takenalong the view line 31-31 in FIG. 29.

FIG. 32 is a view of a detachable needle assembly that attaches to thetissue engagement device of FIG. 28.

FIG. 33 is a detailed, exploded view of a proximal end of the detachableneedle.

FIG. 34 depicts an embodiment of an engagement arm that is compatiblewith tissue engagement devices, the engagement arm featuring a shieldprotrusion capable of preventing inadvertent tissue injury when pullingthe engagement arm while it is actuated and/or limiting the penetrationdepth of the arm into tissue.

FIGS. 35A-35F depict various stages of deployment of another embodimentof a tissue engagement device that includes alternate engagement armswith shield protrusions.

FIG. 36 depicts an illustrative rapid retraction mechanism adapted to athreaded coupling between a needle assembly and a device handle.

FIG. 37 depicts an embodiment of a device having a lockable collar thatfits over a tube shaft.

DETAILED DESCRIPTION

Illustrative embodiments are described in the following with referenceto the drawings. It should be understood that such embodiments are byway of example only and are merely illustrative of the many possibleembodiments which can represent applications of the principles of thepresent disclosure. Various changes and modifications obvious to oneskilled in the art to which the present disclosure pertains are deemedto be within the spirit, scope and contemplation of the presentdisclosure as further defined in the appended claims. The illustrativeembodiments described herein are not intended to be exhaustive or tolimit the disclosure to the precise forms disclosed in the followingdetailed description. Rather, the illustrative embodiments describedherein are chosen and described so those skilled in the art canappreciate and understand the disclosed principles and practices.

The inventors have recognized that known devices and methods foraccessing the pericardial space, such as those discussed in theBackground above, have been unsuccessful and impractical in clinicaluse. For example, capital equipment and facility connections, such asfor vacuum, are undesirable, increase cost, require maintenance, andtake up space in generally crowded clinical labs. The requiredpenetration angle can vary widely and be very shallow too (e.g. almost 0degrees to almost 90 degrees, with shallow being around 30 degrees orless), and varying approaches to target anterior and inferior areas ofthe heart also make it difficult to engage the pericardium. Further,varying fat and loose connective tissue adjacent the pericardiuminterferes with engagement. Additionally, known devices are not designedspecifically for engaging a tissue layer (versus a thicker mass oftissue like in lead anchoring devices) and do not have features forcreating an access pathway for a guidewire or catheter type device intothe potential space between the tissue layer being engaged and anunderlying tissue layer. Embodiments disclosed herein address,ameliorate, or eliminate one or more of the foregoing limitations and/orother limitations of prior art devices. Certain devices and methods, forexample, can reliably and safely separate the pericardium from theepicardium and facilitate passage of a needle or guidewire into thepericardial space.

Referring to FIG. 1, an anterior view of the thoracic cavity, thepertinent anatomical structures such as the diaphragm 33, left lung 21,right lung 22, aorta 23, and heart 10 are shown. A portion 20 of theparietal pericardium 11 is cut away to so that the underlying epicardium12 and epicardial fat 13 can be seen.

Referring to FIG. 2, a midsection lateral view of the thoracic cavity isshown again showing the heart the pericardium 11 and further showing theepicardium 12, the pericardial space 14, and the liver 15. Foradditional reference the sternum 25 and spine 26 are shown. Thepericardial space 14 exists between the pericardium 11 and theepicardium 12. Under normal conditions, the surfaces of the epicardiumand pericardium enclose a potential space; thus there is minimal to noclearance between the two layers, as described by Swale M. et al,“Epicardial Access: Patient Selection, Anatomy, and a StepwiseApproach.” The Journal 240 (2011). In this figure, an anterior approach31 is depicted, which is a preferred pericardial access approach and oneused most commonly today. This approach is called the anterior approachbecause it provides access into the pericardial space on the anteriorside of the heart. In this figure, inferior approaches 32 and 34 arealso shown, and provide access to the inferior side of the pericardialspace 14. The inferior approach 32 requires passing through thediaphragm 33 and for this reason is also referred to as atransdiaphragmatic or subdiaphragmatic approach. Both the anteriorapproach and 31 and the inferior approach 34 are called subxiphoidapproaches and differ in the angle to the heart.

FIG. 3 shows a view of the chest of a person with the xiphoid process 50and the 1st costal 51 to the 10th costal 60 identified and numberedsequentially (i.e., the 2nd costal 52, 3rd costal 53, etc. through the10th costal 60). An intercostal approach 61 shown here between the 6thand 7th ribs 56, 57 provides direct access to different areas of theheart. In this example, the intercostal space allows the apex of theheart to be accessed, and so such an approach is also called atransapical approach. Limitations to such an approach are the ability toeventually deliver and maneuver catheters because of the steep anglerelative to the heart. The subxiphoid approach 62 is shown and itsposition relative to the xiphoid 50 and the costal margin 63. With theheart always positioned more to a person's left side the subxphoidapproach 62 is angled towards the person's left shoulder area 64.

FIGS. 4 through 6 illustrate an embodiment of a tissue engagement device71 which, referring to FIG. 4, has a handle 72, a tube 73 and a tip 74.The handle 72 has a main body 81 in which sits an actuation lever 75. Inthe illustrated embodiment, the actuation lever 75 extends from a topside 105 of the handle 72 and, more generally, the device 71. Lever 75is shown in the forward position, which is when lever 75 is towardssurface 76 of handle 72 and the engagement arms 96 and 97 (see FIG. 9)are retracted. A bottom side 106 of handle 72 and device 71 is shown inFIG. 5. The lever 75 can be switched to the rear position, which is whenit is towards surface 77, as is also later shown in FIG. 7. A punctureneedle 79, which has a tip 135, as shown in FIG. 6, enters through theproximal end 80 of the handle 72 and emerges through a slot 78. The slot78 is part of a needle pathway 91. FIG. 4 also shows that in theillustrated embodiment, the tube 73 fits into a handle body 81. Thepuncture needle 79 is shown straight but can be alternatively curvedalong any portion, which can help bring the tip 135 closer to the tip 74as the needle 79 is deployed.

FIG. 7 is a detail view of the handle 72, showing where tube 73 entersthe body 81. In this figure, lever 75 is switched to the rear position,which is when engagement arms 96 and 97 (see FIG. 9) are deployed.

FIG. 8 is a perspective exploded view of the handle 72, which showslever 75 and body 81. Covers 82 and 83 fit over the hubs 84 and 85 oflever 75. In this embodiment, the covers 82, 83 are held in place withscrews 85 and 86 that pass through body 81, and thread into covers 82and 83, respectively. The hubs 84 and 85 are received within recessesdefined by the covers 82, 83 and the body 81 of the handle and arepermitted to rotate therein. In this way, the lever 75 can pivotrelative to the main body 81. Tube 73 fits into holes 87 and 88 of body81 and is rigidly attached to body 81. In the illustrated embodiment,tube 73 defines a slot 89 at a proximal end thereof, which allows thepuncture needle (see FIG. 6) to pass through. FIG. 8 also depicts anactuation rod 90 that defines a groove or needle pathway 91 and throughwhich a pin 92 is pressed transversely. In the illustrated embodiment,actuation rod 90 fits inside of tube 73 and slides freely within. Statedotherwise, the tube 73 defines a lumen 99 that is sized to receive theactuation rod 90 therein. Stated otherwise, in some embodiments, thelumen 99 can define a maximum interior width that is larger than amaximum exterior width of the actuation rod 90. In the illustratedembodiment, the lumen 99 is sufficiently large to permit the actuationrod 90 to translate freely or within the tube 73. Lever 75 has grooves93 and 98 that extend into the hubs 84 and 85 and are sized to receiverespective ends of the pin 92 therein. In the illustrated embodiment,the pin 92 position is not on the same axis as the hubs 84 and 85, sothat as lever 75 is pivoted it can move and control the position ofactuation rod 90. Stated otherwise, in the illustrated embodiment, thepin 92 position is not restricted to a rotational axis of the hubs 84and 85, or is capable of translating or otherwise moving relative to arotational axis through the hubs 84, 85. Rotation of the lever 75, andthus of the hubs 84, 85, can result in a forward or rearward camming ofthe pin 92, which can translate the actuation rod 90 in a distaldirection or a proximal direction, respectively. In order to accommodatethe pin 92 motion, the tube 73 has a cutout 94.

FIGS. 9 and 10 are close-up cutaway views of the tip 74 of the device 71showing engagement arms 96 and 97 in their retracted and deployedpositions, respectively. In the illustrated embodiment, the engagementarms lie directly adjacent or very close to each other. The tube 73 hasslot 100 and is shown with the actuation rod 90 in place. Actuation rod90 has tip 104, slot 101 and posts 102 and 103 on which the arms 96 and97 are placed and each can pivot about. Guide 110 is shown with post 111that fits into a hole 112 in tube 73 to hold it in place. In theembodiment shown, the tip 113 of guide 110 has a chamfered face 114which aligns with the chamfered end 115 of tube 73. This chamfered face114 is on the same side as the bottom side 106 identified in FIGS. 5 and6. Stated otherwise, in the illustrated embodiment, the chamfered face114 is at a bottom side of the device 71. Guide 110 also has guide post116 extending from it. Arms 96 and 97 also have slots 117 and 118 (seealso FIG. 16A) into which post 116 slides. Slots 100, which arepositioned at opposite sides of the tube 73 in the illustratedembodiment, allow engagement arms 96 and 97 to pivot and extend beyondthe external boundaries of tube 73 during deployment. Chamfered face 114and chamfered end 115 allow arms 96 and 97 to be positioned and be movedmore closely to a tissue layer when the angle between the tip 74 and thesurface of the tissue layer to be engaged is shallow, as compared, forexample, with an arrangement in which a transverse cross-sectionalprofile of the tube 73 and/or the guide 110 is not reduced or isunaltered along the distal end of the device 71. The chamfered face 114and chamfered end 115 may be said to define an acute angle relative tothe longitudinal axis AL of the device 73 (which is also a longitudinalaxis of the tube 73, in the illustrated embodiment). This angledconfiguration can permit the chamfered faces 114, 115 to rest against atissue layer (e.g., the layer 130 described below) while the tube 73 isat an acute angle relative to the tissue layer.

Now referring to FIG. 4, and FIGS. 6 through 10, as the lever 75 movesfrom its forward position shown in FIG. 4 to its rear position shown inFIGS. 6 and 7, the actuation rod 90 moves backwards from its positionshown in FIG. 9 to its position shown in FIG. 10. Stated otherwise, ascan be seen by comparing FIGS. 9 and 10, the actuation rod 90 isretracted into the tube 73. In FIG. 9, the tip 104 of the actuation rod90 extends past a distal face 120 of the tube 73. In FIG. 10, a greaterportion of the tip 104 has been drawn into an interior of the tube 73and a distal face 121 of the tip 104 extends only slightly past thedistal end of the tube 73 in an axial direction. In some embodiments,the tip 104 may be drawn fully into an interior of the tube 73 such thatthe distal face 121 of the tip 104 is either flush with or axiallyrecessed relative to the distal face 120 of the tube 73. The lever 75controls the actuation rod 90 motion because of how the two areconnected together via the pin 92 and grooves 93 and 98 in which the pin92 follows, as discussed previously. The backward movement of actuationrod 90 causes the arms 96 and 97 to pivot about posts 102 and 103 as theslots 117 and 118 of arms 96 and 97 interact with the fixed guide post116. In particular, the slots 117, 118 follow along the fixed guide post116 to cam the arms to the outstretched, deployed, or expandedconfiguration, as discussed further below. When the actuation rod 90 isfully retracted, then arms 96 and 97 are fully deployed, as shown inFIG. 10.

FIGS. 11 and 12 further illustrate the deployment motion of tip 74,specifically showing tip 74 in different states or stages as actuationrod 90 is moved backward relative to the tube 73 to move arms 96 and 97from their retracted or undeployed state to their deployed state. FIG.11 shows side views of the distal portion of the device 71 in thedifferent states, and FIG. 12 shows perspective views of the distalportion of the device 71 these same states. Each figure includes alegend identifying a forward (or distal) direction and a backward (orproximal) direction. In the retracted state, which corresponds with theleftmost orientation in FIGS. 11 and 12, the tip 104 is positioned inalignment with the penetrating tips 132 and 133 of arms 96 and 97.Stated otherwise, the penetrating tips 132, 133 the distal-most edges ofthe arms 96 and 97 are level or flush with the distal face 121 of thetip 104 of actuation rod 90 in the axial direction. Moreover, in theillustrated embodiment, the outer edges of the arms 96, 97 define arounded profile that substantially matches (e.g., is substantially flushwith) a rounded profile defined by the tip 104. When the arms 96, 97 arein the retracted or undeployed state, there is a close correspondencebetween an outline of the arms 96, 97 and an outline of the tip 104.

With continued reference to FIGS. 11 and 12, the outer profile definedby the moving arms 96, 97 extends outwardly beyond the profile of thetip 104 during deployment of the arms 96, 97. In the illustratedembodiment, the arms 96, 97 extend past the distal face 121 of the tip104 in the axial direction throughout deployment as the actuation rod 90is retracted. Indeed, in the illustrated embodiment, at least a portionof each arm 96, 97 is positioned distally relative to the distal face121 of the tip 104 in each of the five stages or orientations depictedat the right side of FIG. 12.

A distance between the distal face 121 of tip 104 and the penetratingtips 132 and 133 of the arms 96, 97 can be controlled by changing thegeometry of arms 96 and 97. For example, the penetrating tips 132 and133 can be either distally beyond, in alignment with, or proximallyretracted relative to the distal face 121 of the tip 104. Changing thisrelative distance can influence the depth to which the arms 96 and 97penetrate into tissue as they are actuated. In certain embodiments,penetrating tips 132 and 133 are positioned proximal of the distal face121 by a distance of between 0 inches and 0.030 inches when the arms arein the retracted state (e.g., the leftmost configuration in FIG. 11). Itis contemplated that penetrating tips 132 and 133 could also be atdifferent positions relative to each other (e.g., at different axialdepths and/or radial distances from the longitudinal axis AL of thedevice 71). As arms 96 and 97 actuate from retracted to fully deployed,their penetrating tips 132 and 133 approach then bypass each otherbefore stopping in positions radially extended from tube 73.

Referring now to FIGS. 11 and 13A-13F, in some embodiments, the tips132, 133 of the arms 96, 97 define a gap or space d between them whenthe arms 96, 97 are in the undeployed state. As tip 104 is pressedagainst soft tissue, a bulge of tissue forms in space 139. The gap orspace d can be sized such that a layer of thin tissue 130 willpreferentially bulge into space 139 but underlying tissue 131 (i.e., atissue layer that is beneath the tissue layer being engaged) will not. Atransverse width of the space d may be customized for a specificapplication; for example, when used to engage perineal membrane with athickness of 0.020 to 0.040 inches (0.5 to 1.0 mm), a width d ispreferably twice the membrane thickness, or approximately 0.040 to 0.060inches (1.0 to 2.0 mm). It is further contemplated that in someembodiments, the starting width of the space d may advantageously bezero or substantially zero; i.e., there is no gap between the tips 132,133 when the arms 96, 97 are undeployed. In some embodiments, tips 132,133 that do not define a space d in the retracted state may each be inalignment with the longitudinal axis AL of the device 71. In otherembodiments, the space d is less than 0 inches when the arms 96, 97 areundeployed. Stated otherwise, the tips 132 and 133 may already be in abypassed configuration when in the undeployed state.

Stated in yet another manner, in the illustrated embodiment, the tips132, 133 face toward each other in the undeployed state that is depictedin the leftmost orientation of FIGS. 11 and 12 and in FIG. 13A. In thisstate, the tips 132, 133 are at opposite sides of the longitudinal axisAL of the device 71 and are directed inwardly (e.g., transverselyinwardly or radially inwardly), and in the illustrated embodiment, aredirected toward the longitudinal axis AL. Stated otherwise, the tips132, 133 may be said to face toward an imaginary longitudinal plane thatpasses through the longitudinal axis AL. In the illustrated leftmostconfiguration of FIG. 11, the imaginary longitudinal plane isperpendicular to the plane of the page and extends through thelongitudinal axis AL. As the arms 96, 97 are transitioned to thedeployed state, the tips 132, 133 move in opposite directions relativeto the longitudinal axis AL, or stated otherwise, relative to thelongitudinal plane that extends through the longitudinal axis AL. In theillustrated orientation, the arm 96 rotates in a clockwise direction tomove the tip 132 substantially leftward and upward (e.g., proximally),and the arm 97 rotates in a counterclockwise direction to move the tip133 substantially rightward and upward (e.g., proximally). In thismanner, the arms 96, 97 rotate through the imaginary longitudinal planeand past each other. Stated otherwise, the tips 132, 133 bypass eachother in opposite directions. In each of the second through sixthorientations depicted in FIGS. 11 and 12 (counting from left to right),and in FIGS. 13B-13F, the tips 132, 133 have bypassed each other andmove progressively further away from each other. That is, even as of thesecond orientation of FIGS. 11 and 12 (counting from left to right) andas of the orientation of FIG. 13B, the tips 132, 133 have passed thelongitudinal axis AL and move laterally, transversely, or radiallyoutwardly and away from each other and from the longitudinal axis AL. Itmay also be said that after the tips 132, 133 bypass each other, theyface outwardly or face away from each other. They likewise may be saidto face away from the longitudinal axis AL of the device 71. In theillustrated embodiment, the tips 132, 133 face each other, or faceinwardly, in the undeployed state. In other embodiments, the tips 132,133 can face away from each other, or face outwardly, in the undeployedstate.

With reference to FIG. 11, in the retracted or undeployed state, thearms 96, 97 define an outer profile having a maximum lateral width W. Inthe illustrated embodiment, the width W is less than a maximum exteriorwidth or diameter D defined by the tube 73. It is noted that the terms“diameter” and “tube” do not necessarily imply a cylindricalconfiguration of the tube 73. Although the illustrated embodiment of thetube 73 is substantially cylindrical, other suitable shapes andconfigurations of the tube 73 are contemplated. In the illustratedembodiment, when the device 71 is in the undeployed state, the size ofthe gap d is less than the maximum lateral width W of the arms 96, 97,which is smaller than the maximum exterior width D of the tube 73. Thearms 96, 97 may thus have a smaller transverse profile than does thetube 73 when in the undeployed state.

As can be appreciated from the rightmost orientation in FIGS. 11 and 12and from FIG. 13F, when the arms 96, 97 are fully deployed, the arms 96,97 can have a larger transverse profile than the tube 73. Statedotherwise, the distance between the tips 132, 133 can be greater thanthe maximum exterior width D of the tube 73 when the arms 96, 97 aredeployed.

With reference again to FIG. 11, in the illustrated embodiment, the tips96, 97 are configured to move only in transverse and proximal directionsrelative to the tube 73. Stated otherwise, in the illustratedembodiment, throughout deployment of the arms 96, 97, the tips 132, 133of the arms 96, 97 do not move distally relative to the tube 73. Therightmost depiction in FIG. 11 includes a path 125 that is traveled bythe tip 133 during deployment of the arms 96, 97. The illustrated path125 is arc shaped and may, in some instances, be substantiallysemicircular (other arc shapes may also be defined in furtherembodiments). Moreover, in tracing the arc-shaped path 125, no componentof movement of the tip 133 is directed distally. Rather, the movementonly includes rightward (transverse) and upward (proximal) components inthe depicted orientation. Moreover, during the early stages ofdeployment, the movement is primarily transverse, whereas in laterstages, the movement increasingly includes proximal components. The tip132 traces a path having the same arc shape, but does so in the oppositetransverse direction. However, the tips 132, 133 move in unison witheach other in the proximal direction. In other embodiments, some amountof distal movement is possible for the tips 132, 133 during the earlystages of deployment.

As can be appreciated from the foregoing discussion, and with additionalreference to FIGS. 13A-13F, the paths traced by the tips 132, 133 duringdeployment can be well suited for engaging the thin tissue 130. Forexample, as previously mentioned, the gap 139 between the tips 132, 133can receive a bunched portion of the thin tissue 130 therein when thedistal end of the device 71 is pressed against the tissue layers 130,131. As the tips 132, 133 are deployed, they initially move primarily inthe transverse direction, or without moving toward the underlying tissuelayer 131. Accordingly, the tips 132, 133 can engage the upper, thintissue 130 without engaging the underlying tissue layer 131. As the tips132, 133 continue along the arc-shaped paths through the later stages ofdeployment, the thin tissue 130 is further engaged by the arms 96, 97and, with more proximally directed components of movement, is liftedaway from the underlying tissue layer 131.

With reference again to the rightmost depiction in FIG. 11, and withadditional reference to FIG. 16A, the arms 96, 97 can define curvededges 127, 128, which may also be referred to as rounded sides, thatextend from the tips 132, 133, respectively. With yet additionalreference to FIGS. 13A-13F, as the tips 132, 133 move along thearc-shaped paths during deployment of the arms 96, 97, the curved edges127, 128 can smoothly pass over the underlying tissue layer 131 withoutengaging this tissue. Stated otherwise, the curved edges 127, 128 caninhibit trauma to the tissue layer 131 tissue positioned beneath thelayer 130 as the curved edges 127, 128 rotate against the tissue layer131. In some embodiments, the curved edges 127, 128 face distally fromthe tissue engagement device 71 throughout an entirety of a transitionfrom the retracted orientation to the actuated orientation to inhibittrauma to the additional tissue.

With reference again to FIGS. 11 and 12, mechanics of the deployment ofthe arms 96, 97 is further discussed. As the actuation rod 90 movesbackward it moves the proximal portions of the arms 96 and 97 backwardsrelative to the guide 110 and the post 116. The grooves 117 and 118 ofarms 96 and 97 follow along post 116, and cause arms 96 and 97 to pivotabout posts 102 and 103. Stated otherwise, movement of the grooves 117,118 relative to the post 116 causes the arms 96, 97 to cam or rotate inopposite directions. The motion of tip 104 relative to penetrating armtips 132 and 133 (e.g., the amount of axial distance between the distalface 121 and the tips 132, 133) can be modified by changing theinteraction between the pivots and groove 117 and 118 geometry. It iscontemplated that design variations can include configurations in whichthe tip 104 moves axially faster or slower than the axial displacementof penetrating tips 132 and 133. It is also contemplated that the tip104 could remain fixed relative to the movement of penetrating tips 132and 133. This relative movement can influence penetration depth intotissue.

FIGS. 13A-13F show specifically how the same deployment motion andmethod described in FIGS. 11 and 12 is used to engage a tissue layer 130that sits directly on top of underlying tissue 131. The deploymentmethod and engagement with tissue is a continuous motion but for clarityis shown in discrete stages in each of FIGS. 13A-13F.

FIG. 13A demonstrates that the tip 74 of device 71 (with arms 96 and 97in the retracted state) is pressed against tissue 130 with enough forcethat both tissue layer 130 and underlying tissue 131 are slightlydepressed. This results in slight bulging of tissue between arms 96 and97; however, because of the controlled width d between the tips 132,133, only tissue layer 130 fully bulges into space 139 betweenpenetrating tips 132 and 133. The resultant effect is that aspenetrating tips 132 and 133 rotate toward each other between theillustrated stage and that depicted in FIG. 13B, the tips 132, 133 pinchonly tissue 130 while displacing underlying tissue 131 away. In someinstances, the rounded edges 127, 128 can assist in pushing away theunderlying tissue 131 without engaging it. Continuing this motion, aspenetrating tips 132 and 133 bypass each other, rotating in oppositedirections, they pierce tissue 130 without puncturing underlying tissue131.

With reference to FIGS. 13B-13E, lever 75 (see FIGS. 4-7) istransitioned from its forward position towards its rear position causingactuation rod 90 to move backward relative to the tube 73 and causingarms 96 and 97 to pivot. As the arms 96 and 97 continue to pivot, theirtips 132 and 133 extend further underneath tissue layer 130 andgradually lift it away from underlying tissue 131. For example, the tips132, 133 can engage an interior surface of the tissue layer 130. Inother instances, the tips 132, 133 may not pierce through a fullthickness of the layer 130. Rather, the tips 132, 133 may embed withinor otherwise engage the tissue layer 130 without passing through it. Ineither case, as the arms 96, 97 rotate in opposite directions, the arms96, 97 apply tension to the tissue layer 130 in opposite directions.

FIG. 13F depicts the arms 96 and 97 in their fully deployed state, andthe tips 132 and 133 are underneath the tissue layer 130. The entiredevice 71 can be maneuvered or pulled back to further manipulate tissuelayer 130 from underlying layer 131, and increase the space 134 betweenthe two layers 130, 131. In certain applications, the space 134 is thepericardial space of a patient's heart.

FIGS. 14A-14E depict stages of a method in which the arms 96 and 97 areused in conjunction with the puncture needle 79 (introduced and shown inFIG. 6) when engaging tissue layer at a shallow contact angle relativeto tissue layer 130. One or more of the stages of this method can becombined with the method for engaging a tissue layer depicted in FIGS.13A-13F. With reference to FIG. 14A, the device 71 is pressed againstand depresses tissue layer 130 and underlying tissue 131. This is asimilar method stage to that shown in FIG. 13A. As shown, for example,in FIGS. 9 and 10, the distal face 121 of the tip 104 of actuation rod90 is relatively blunt making it very safe to press hard against tissuewithout risk of puncturing through the tissue. For example, the tip 104is sufficiently blunt to be pressed against the tissue layers 130 or 131without penetrating them. This is also true where the tip 104 contactsthese layers at contact angles greater than the contact angle depictedin FIG. 14A. In the illustrated embodiment, the puncture needle 79 isloaded into device 71 and is positioned so that the tip 135 passesthrough actuation rod 90 and emerges from tube 73 through opening 78(seen in FIGS. 5 and 6).

FIG. 14B shows how the engagement arms 96 and 97 have been deployed toengage tissue layer 130 and lift it away from underlying tissue 131.This stage is similar to that depicted in FIG. 13E.

With reference to FIG. 14C, the puncture needle 79 can be advancedforward (distally) until the tip 135 punctures through tissue layer 130.Prior to advancing the tip 135 in this manner, the tissue layer 130 maybe further lifted from the underlying layer 131 be pulling back on thedevice 71 to expand the space 134. Such expansion of the space 134 isalso depicted in FIG. 14C, as can be appreciated by comparing thisfigure with FIG. 14B.

With reference to FIG. 14D, the puncture needle 79 continues to beadvanced forward until the entire tip 135 is inside the space 134between tissue layer 130 and underlying tissue 131. FIG. 14E shows how astandard guidewire 136 (in some embodiments, the guidewire can have adiameter of from about 0.014 inches to 0.035 inches) can be passed downa lumen of the puncture needle 79 and into the potential space 134created by (e.g., defined between) the tissue layer 130 and underlyingtissue 131.

In many applications, the portion of the device 71 shown in FIGS.14A-14E will be in tissue and not directly seen by a user. At anysuitable point during the method (e.g., at or between any steps shown inFIGS. 14A-14D) it is possible to inject contrast media, or other agentsor materials, so that the area outside the tip 135 of needle 79 can beseen with fluoroscopy or any other suitable imaging technique to aidvisualization.

FIGS. 15A-15D show how the device 71 and certain features thereof can beused to overcome, for example, the challenge in gaining access throughthe pericardium due to fat and loose connective tissue. In thesefigures, the fat and loose connective tissue is identified withreference numeral 140 on the surface of the pericardium, which would beequivalent to tissue layer 130. Tissue 140 has different mechanicalproperties than tissue layer 130 and underlying tissue 131 and can bemore easily pushed apart with a blunt dissection method.

With reference to FIG. 15A, a method can include pushing the tip 74 ofdevice 71 against the surface tissue 140. As shown in FIG. 15B, thelever 75 (see FIGS. 4-7) is actuated to cause arms 96 and 97 to deploy.The arms are shown fully deployed in FIG. 15B.

With reference to FIG. 15C, while forward pressure is applied to thedevice 71, the lever 75 is cycled forward and backward, causing arms 96and 97 to cyclically deploy and retract, which is shown by thebidirectional arrows 141 and 142. This can be repeated, and typically nomore than 2 or 3 times (cycles) should be needed to fully penetratethrough the tissue layer 140. Any suitable number of actuation cycles ispossible to achieve the desired penetration.

FIG. 15D depicts how the cycling method just described can allow the tip74 to tunnel or dissect through the tissue layer 140 and bring it muchcloser to the target tissue layer 130. Additional cycling, whileadvancing the device forward, may be employed to bring the tip 74 intocontact with the tissue layer 130 (but this additional tunneling to thelayer 130 is not explicitly shown here).

FIG. 16A shows a top plan view of an embodiment of arms 96 and 97 thatmay be used in the device 71. In the illustrated embodiment, the arms 96and 97 are identical and flat, which can help to reduce the overall costof the device 71. As they are flat, the arms 96 and 97 can be made fromstock sheet material using, for example, laser cutting, water jetcutting, photo etching, or stamping processes, and the like, which arelow cost. Any suitable material is contemplated for the arms 96, 97,including metal, biocompatible plastic, etc. The arms 96, 97 can besubstantially rigid, in some embodiments. The arms 96 and 97 have holes150 and 151 and grooves 117 and 118, respectively. The centerlines 152and 153 pass through holes 150 and 151, and the center of grooves 117and 118, respectively. The orientation of the tips 132 and 133 isdefined by axis 154 and 155. The tips 132 and 133 have straight insideedges 172 and 173, which may also be referred to as shelves. As shown inFIG. 13F, the tissue layer 130 may rest on the shelves 172, 173 when thearms 96, 97 are deployed. Stated otherwise, the shelves 172, 173 mayextend laterally to engage a lower surface of the tissue layer 130. Theshelves 172, 173 may aid in pulling the tissue layer 130 away from thetissue layer 131.

With reference to FIG. 16B, in some instances, it may be desirable toincrease the sharpness near tips 132 and 133. This may be accomplished,for example, by adding one or move bevel planes 175 that are at anglesrelative to the main planar orientation of the arms 96, 97. Any othersuitable sharpened configuration is also contemplated.

Many different embodiments of the arms are contemplated. FIG. 17 depictsanother embodiment of arms 160 and 161 with different tip angles thanthose of the arms 96 and 97. The arms 160 and 161 have holes 162 and163, and grooves 164 and 165. Centerlines 166 and 167 pass through thecenters of grooves 164 and 165, and holes 162 and 163. The arms 160 and161 differ from the arms 96 and 97 in that the orientation of tips 168and 169 defined by axes 170 and 171 are at a greater angle relative tocenterline 166 and 167 than axis 154 and 155 are to centerlines 152 and153 in FIG. 16A. The tips 168 and 169 have straight inside edges 174 and175. In some arrangements, the larger angle of the arms 160, 161 canresult in a larger gap between the tips of the arms 160, 161 in anassembled device that is in the retracted state, as compared, forexample, to the gap 139 in FIG. 11.

FIG. 18 depicts another embodiment of arms 180 and 181 with differenttip angles and tip inside edges than the arms 96 and 97. The arms 180and 181 have holes 182 and 183, and grooves 184 and 185. Centerlines 186and 187 pass through the centers of grooves 184 and 185, and holes 182and 183. The arms 180 and 181 differ from the arms 96 and 97 in that theorientation of tips 188 and 189 defined by axis 190 and 191 are at agreater angle relative to centerline 186 and 187 than axis 154 and 155are to centerlines 152 and 153 from FIG. 16A. In the illustratedembodiment, the angles are the same as those for the arms 160, 161 ofFIG. 17. The tips 188 and 189 of the arms 180, 181 include serratedinside edges 192 and 193, which can assist in engaging the tissue layer130.

FIG. 19 shows a perspective view of a distal end of the puncture needle79. The needle 79 includes a tube 200 with axis 203. The tube 200 ispreferably round but can be any shape. Tip 135 has an opening 201 anddistal edge 202. The opening 201 faces away from the main axis 203 andprevents coring of tissue that can enter the distal opening 201 as theneedle 79 is pushed along its axis 203 through tissue. Stated otherwise,the needle 79 can be a non-coring needle. Other embodiments can begenerally any shape (e.g., any suitable cross-sectional configuration)and can provide any suitable orientation for opening 201. The tube 200can define a lumen 205 that is used as a delivery pathway for accessorydelivery, such as a guidewire and/or contrast media during the accessapproach, as previously discussed.

FIGS. 20 and 21 depict another embodiment of a needle 300 and anembodiment of a mating handle 400, which enables improved motion controlof the needle 300 (relative to motion control of the needle 79), andimproved means to deliver contrast media and guidewire accessories. Theneedle 300 includes a tube 301 and a tip 302 with opening 303. A fitting304 is attached to the proximal end of needle 300. The fitting 304includes a distal hub 305, a thread 306, and a proximal hub 307. A Luertype connection 320 is integrated into the proximal end of the fitting304 with ears 308 and 309, and guides 310 and 311. The needle 300interfaces with the handle 400.

As shown in FIG. 21, the handle 400 includes a body 401 and a knob 402that is threaded onto the needle thread 306. The handle 400 also haslever 404 with hubs 406 (such as the hubs 84, 85 in FIG. 8). Covers 407and 408 are fastened using screws 409 and 410 to the handle body 401,and are positioned over the lever hubs 406 so that lever 404 can pivot.Cover 411 is fastened to handle body 401 using screws 412 and 413, andis positioned over the needle fitting distal hub 305 so that fitting 304is guided through handle body 401. The handle body 401 has matchinginternal grooves (not visible) for guides 310 and 311, which keepfitting 304 from rotating as knob 402 is rotated.

In use, the knob 402 can be rotated in either direction, which advancesor retracts needle 300 without letting the needle 300 rotate. Statedotherwise, rotation of the knob 402 can result in distal or proximaltranslation of the needle 300. The Luer connection 320 is the commonstandard type used to interconnect fluid fittings and syringes together.Any other suitable connection interface is contemplated.

The Luer connection 320 can enable additional other functions. Oneexample is that a syringe with contrast media can be connected to theLuer fitting 320, so that as the device 71 is being advanced towards theheart, contrast can be injected to verify the position continuouslyduring the approach. A second example is that once the puncture needle300 has been placed into the pericardial space, a means for delivering aguide wire into the pericardial space is established. Once a guidewireis delivered, the device 71 can be removed leaving the guidewire inplace, which then provides the means to deliver other medical devicessuch as sheaths and in turn then mapping and ablation catheters.

FIGS. 22A and 22B depict another embodiment of a tissue engagementdevice 510. The device 510 is shown in an undeployed state in FIG. 22Aand is shown in a deployed state in FIG. 22B. The device 510 defines aneedle pathway 500 that is either parallel to or collinear with acentral axis of an outer or main tube 501. The needle pathway is between(e.g., extends between) tissue engagement arms 502 and 503. In thisembodiment the needle pathway 500 is integral to (or defined by) theactuation rod 504. The device 510 includes a pin 505 that is attached tothe actuation rod 504. The arms 502, 503 are pivotally coupled to thepin 505 at opposite sides of the needle pathway 500. In this respect,the arms 502, 503 are spaced further apart than they are in the device71 described above. Engagement arms 502 and 503 have grooves 506 and 507respectively. Pins 508 and 509 are fixed in a position through main tube501. Stated otherwise, the pins 508 and 509 are attached to the maintube 501. As actuation rod 504 is pushed forward (e.g. distally) itmoves engagement arms 502 and 503 with it, which in turn pivot about pin505 as their grooves 506 and 507 engage pins 508 and 509 and cause thepivoting motion. Referring to previous figures, this is different thanthe device 71, where two pivot points were used and a single posteffected camming of the arms. Here, a single pivot axis is used (i.e.,the axis passing through the post 505), and two separate pins 508 areused to individually effect rotation of each arm 502, 503. Anotherdifference is the actuation rod 504 moves forward (distally) rather thanbackwards (proximally) to deploy the engagement arms 502, 503 in thepresent embodiment. The needle path 500 is also parallel to the sidewallof the shaft or tube 501 and is fully encompassed thereby, whereas theneedle path 91 of the device 71 is angled relative to its tube 73 andpasses through the sidewall thereof, as seen in FIG. 6.

FIGS. 23A and 23B show another embodiment of a tissue engagement device520 that defines a straight needle path 526 that is parallel to the maintube 521. Unlike with the device 510, however, the needle path 526 doesnot pass between the engagement arms 524, 525. Rather, the needle path526 is above the engagement arms 524 and 525 in the depictedorientation, or stated otherwise, the needle path 526 is laterallyoffset from the engagement arms 524, 525. The device 520 includes anactuation rod 522 to which engagement arms 524 and 525 are connected bypins (not shown). In a similar way as disclosed herein, actuation rod522 is used to deploy and retract engagement arms 524 and 525. Thedevice 520 includes a stationary tip 523 that defines a needle opening529. The tip 523 guards both the top and bottom sides of the engagementarms 524 and 525, in the illustrated orientation. Stationary tip 523 isfixedly attached to the distal end of main tube 521.

FIGS. 24A and 24B depict yet another embodiment of a tissue engagementdevice 540 in undeployed and deployed states, respectively. The device540 defines a straight needle path 550 that is parallel to a main tube541 and is positioned above engagement arms 544 and 545. As with priorembodiments described herein, the engagement arms 544 and 545 aredeployed by axial movement of actuation rod 542. The needle path 550 isdefined by the actuation rod 542 and is bordered along an upper endthereof by the tube 541.

FIGS. 25A-25C are detailed images of distal tips of further embodimentsof tissue engagement devices 580, 581, 600 that are actuated indifferent manners; in particular, FIGS. 25A, 25B depict the differencesbetween a pull versus a push actuation motion where engagement arms arepivotally mounted to an actuation rod. In FIG. 25C, the engagement armsare pivotally mounted to the tube.

In FIG. 25A, the device 580 includes a tube 560, an actuation rod 562,and engagement arms 564, 565. The tube 560 has a distal edge 561 andactuation rod 562 has a distal edge 563. As actuation rod 562 is pulledand moves proximally relative to the tube 560, the engagement arms 564and 565 move from a retracted state to a deployed state in a mannersimilar to those described above.

In FIG. 25B, the device 581 includes a shaft or tube 570 that has distaledge 571. An actuation rod 572 has distal edge 573. Engagement arms 574and 575 are pivotally mounted to the actuation rod 572. As actuation rod572 moves distally (e.g., is pushed) relative to the tube 570, theengagement arms 574 and 575 move from a retracted state to a deployedstate. The means by which this actuation is achieved is not limited tothe particular arrangement shown.

FIG. 25C depicts another embodiment of a tissue engagement device 600that includes a sheath, shaft, or tube 610 and an actuation member oractuation rod 620. The device 600 further includes engagement arms 630,631 similar to engagement arms disclosed above. The engagement arms 630,631 define camming grooves 632, 633, respectively. The actuationmechanisms are similar between the engagement devices 581 and 600,except that the engagement arms 630, 631 are pivotally attached to thetube 610, rather than being pivotally attached to the actuation rod 620.In particular, both engagement arms 630, 631 are configured to pivotabout a common axis that passes through a pivot post 640, which post isfixedly secured to the tube 610. Two camming posts 641 642 are fixedlysecured to the actuation rod 620. The device 600 is transitioned fromthe retracted state to the deployed state by moving the actuation rod620 proximally relative to the tube 610. Conversely, the device 600 istransitioned from the deployed state to the retracted state by movingthe actuation rod 620 distally relative to the tube 610. As with theactuation rod 90 depicted in FIGS. 9 and 10, which defines a slot 101,the actuation rod 620 can define a slot 650. The slot 650 can be sizedto permit passage of the pivot post 640.

Any other suitable arrangement is contemplated for actuating theengagement arms. For example, in some embodiments, one or moreengagement arms can be pivotally mounted to an actuation rod, one ormore additional engagement arms can be pivotally mounted to the tube,and relative movement between the actuation rod and the tube (to whichone or more camming posts may be mounted) can transition the actuationarms between the retracted and deployed states.

FIG. 26 depicts a method 800 for engaging tissue. The method 800 hasbeen described previously herein, and it should be understood that anysuitable combination of steps of the method are contemplated. Forexample, the method 800 includes nine stages or steps 801, 802, 803,804, 805, 806, 807, 808, 809. Any suitable combination of the steps iscontemplated. Thus, for example, a method 820 can include the steps 803,804, and 806, while other steps (such as the step 805) are omitted. Themethod 820 may be considered a core method that may be common tonumerous methods that employ various permutations of the steps 801through 809.

At step 801, the distal end of a tissue engagement device (e.g., asurgical grasping instrument), such as any of the devices disclosedherein, is introduced inside the body of a patient. Any suitable methodfor introducing the tissue engagement device is contemplated, includingthose known in the art for introducing trocars or other small diameterinstruments into a patient.

At step 802, the distal end of the instrument is guided toward a regionof soft tissue. Any suitable guiding techniques are contemplated,including fluoroscopy methods such as previously mentioned.

At step 803, the distal end of the tissue engagement or graspinginstrument is pushed against the region of soft tissue. As previouslydiscussed, in various embodiments, the grasping instrument can include aplurality of engagement (e.g., penetrating) tips that can, in someinstances, define a gap into which a thin layer of tissue is received.

At step 804, two or more piercing elements are deployed. The piercingelements can include tips that approach and then bypass one another. Thetips may then move to radially extended positions as they pass into thetissue. Step 804 can correspond, for example, to the steps disclosed inFIGS. 13A-13F.

At step 805, the two or more piercing elements are retracted and theyredeployed. Step 805, repeated iteratively, can correspond with themethod described with respect to FIGS. 15A-15D.

At step 806, the tissue is manipulated while the piercing elements aremaintained in the deployed position so as to maintain a grasp on thesoft tissue layer. For example, the tissue engaging or grasping devicecan be pulled in a proximal direction to provide additional spacebetween adjacent tissue layers (e.g., to enlarge the pericardial space).This step can correspond with the stage depicted, for example, in FIGS.14B and 14C.

At step 807, additional procedures are performed, such as passing adelivery needle through the soft tissue and passing a guidewire throughthe needle. This step can correspond with the stages depicted, forexample, in FIGS. 14C-14E.

At step 808, the soft tissue is released as the piercing elements areretracted to their original position. Stated otherwise, returning thepiercing elements to the undeployed state effects a release of the softtissue.

At step 809, the surgical grasping device is fully removed from thepatient. In some instances, the device may be removed over other devicesor instruments that may remain in the body. For example, the guidewireand/or instruments introduced into the body over the guidewire mayremain in place.

In some instances, steps 801 and 802 are examples of steps or actionsthat may be required in order to proceed to step 803, in which theengaging instrument or device invention is pressed against the tissue.The steps 803, 804, 806 of the method 820 are described elsewhereherein, and can include the layer engagement methods that use engagementarms that uniquely deploy radially and pass by each other duringdeployment.

In some instances, step 807 may employ a threaded advancementmethodology like that shown in FIGS. 20 and 21, which can provides acontrolled means for advancing the puncture needle 301 and a means forthe needle 301 to stay in position when the user lets go. This type ofadvancement mechanism may, in some instances, limit the tactile feedbackto the user of the needle tip 302 as it is penetrating through tissue.

FIGS. 27A and 27B depict another embodiment of a tissue engagementdevice 821. The device 821 includes a different mechanism formaintaining the puncture needle in a desired position. The device 821includes a handle 820 having main body 822. In FIG. 27B, a punctureneedle 823 is shown in channel or lumen 833. A transverse slot 824constrains brake pad 825 to have only back and forth motion 827. Thebrake pad 825 has a sloped surface 836 that faces the needle 823. Knob828 has a threaded shaft 829 that feeds into a threaded opening 832 sothat as knob 828 is turned, it rotates about axis 831, which creates theback and forth (e.g., transverse) motion 827. Brake pad 825 only movesin one direction 827, which is preferably transverse to the deploymentdirection and long axis of puncture needle 823. In this way, then asbrake pad 825 presses against needle 823 it does not cause anyadditional unwanted motion of the needle 823 along its deploymentdirection (e.g., in a direction into the page in FIG. 27B). The brakepad 825 is connected to threaded shaft 829 so they stay together but thethreaded shaft 829 can independently rotate with rotation motion 830relative to brake pad 825. Alternatively, the brake pad 825 and thethreaded shaft 829 may not be integrated into a single unit, but insteadmay be pressed together by placing a spring (not shown) at the end oftransverse slot 824. In this way, the spring (not shown) presses againstthe end of brake pad 825 and always biases it against the tip ofthreaded shaft 829. These are just two examples of a feature that allowsa user to apply varying amounts of friction to the needle 823. Otherdevices, mechanisms and techniques can be employed as well withoutdeviating from the spirit and scope of the present disclosure.

The embodiments described above employ two engagement arms. However,other or further embodiments may have as few as 1 actuation arm or morethan 2 actuation arms. In embodiments with more than 2 arms, the armsmay be arranged in alternate, interleaving layers and may share commonpivot pins or posts, or use different pivots. Further, the shapes, sizesand overall construct of the one or more engagement arms can varydepending on particular needs and applications.

Moreover, the embodiments described above use a lever as an actuator.However, other forms of a user interface for moving the actuation rodare contemplated. Any suitable actuation mechanism may be employed, suchas, for example, a knob, a sliding button, or any other suitablemechanical interface. Other suitable forms of actuation includepneumatic, electromechanical, or hydraulic for example. In general, anysuitable actuation mechanism for transitioning the engagement armsbetween deployed and undeployed configurations are contemplated.

FIGS. 28A-30 illustrate yet another embodiment of a tissue engagementdevice 901, which device includes a handle 902, a tube 903, and a tip904. A lever 905 extends from body 911, and is used to actuateengagement arms 926 and 927 within tip 904. When lever 905 is angledtoward tip 904, the engagement arms 926, 927 are retracted. When lever905 is pivoted away from tip 904, the engagement arms 926, 927 areactuated. Needle assembly 950 attaches to handle 902 using a threadedcoupling that joins handle threads 940 with internal threads 960 (seeFIG. 30) on adjustment dial 951. Thus, rotating adjustment dial 951causes needle assembly 950 to advance forward or backward depending onthe direction of rotation. A puncture needle 959 (FIG. 30) is attachedto assembly 950 and passes through a needle pathway 921 within tube 903.

FIG. 29 is a detailed view of handle 902 and needle assembly 950. Analignment rib 954 and needle hub 952 are rigidly affixed (e.g., bondedor overmolded) to penetration needle 959. Needle hub 952 features luerlock threads by which a syringe can be attached to needle assembly 950.Adjustment dial 951 is also fixed to assembly 950, but is notrotationally constrained and can freely spin. Alignment rib 954 is sizedto slideably fit within handle slot 941 and acts to maintain theorientation of needle 959 as adjustment dial 951 is rotated.

FIG. 30 is an exploded, detailed view of handle 902, with needleassembly 950 separated from handle body 911. Needle 959 is affixed torib 954 and hub 952, and extends through needle passage 921 onconnecting rod 920.

FIG. 31 shows a cross sectional view of handle 902 and needle assembly950. The position of needle 959 relative to the other components ofassembly 950 can be readily seen in this view. Hub 952 is attached tothe most proximal location of needle and ends at the female luer cavity955. A taper 956 from cavity 955 provides a transition to ease theinitial insertion of a guidewire (not shown).

FIG. 32 is another view of needle assembly 950, shown in its entirety,including the beveled tip 930 in needle 959. FIG. 33 shows and explodedview of needle assembly 950 that illustrates a mechanism forrotationally indexing the adjustment dial 951. This is achieved with awave spring 965 that is positioned between rib 954 and internal wall 966on dial 951; and a set of angularly spaced detents 967 and pockets 968.Spring 965 pushes dial 951 against hub 952 such that when the detents967 and pocket 968 are aligned, the dial 951 is lightly held inposition. By applying a suitable pitch on the threads 940 (shown inFIGS. 30) and 960, the indexing mechanism can assist the user in gaugingthe advancement distance of the needle tip. For example with indexpositions 90 degrees apart, a thread pitch of 4 millimeters perrevolution would mean that the needle advances 1 millimeter each timedial 951 is rotated to the next index stop. Fixed-distance markings onhandle 902 can provide additional indicators of the advancement distanceof needle assembly 950.

FIG. 34 illustrates another embodiment of an engagement arm 980 that iscompatible with embodiments disclosed herein. In this design, theengagement arm 980 features a protrusion 981 (encircled by dottedcircle) that provides additional advantageous properties. The engagementarm 980 defines a gap 982 with width BB and length DD. This arrangementcan assist in controlling a penetration depth of tip 979 by limiting theamount of tissue that can fit into the gap 982. A height CC of theprotrusion 981 can further provide control by limiting the engagement oftip 979 into tissue prior to the actuation of arm 980. Stated otherwise,the protrusion 981 can inhibit the tip 979 from coming into contact withthe target tissue layer prior to actuation of the arm 980.

FIGS. 35A-35F depict a device 1000 that includes the engagement arm 980and an additional engagement arm 990 of the same configuration (butflipped 180 degrees). These drawings depict various stages of deploymentof the arms 980, 990 from full retraction (FIG. 35A) to full actuation(FIG. 35D). Deployment of a puncturing needle 1002 is shown in FIGS.35D-35F, with the needle being fully retracted in FIG. 35D and fullydeployed in FIG. 35F. In some instances, it can be preferable to fullydeploy the engagement arms 980, 990 to the orientation shown in FIG. 35Dprior to deploying the needle 1002 in the manners shown in FIGS.35D-35F.

As mentioned, the engagement arm 990 can be identical to the arm 980,but may be flipped over such that tips 979, 999 face inwardly (e.g.,toward a longitudinal axis of the device each other when in theretracted orientation. Stated otherwise, arm 980 can lie alongside arm990, but in a mirrored orientation. In the orientation depicted in FIG.35A, the arm tip 979 on arm 980 is opposed by protrusion 991 on arm 990.For example, a distal edge of the tip 979 of the arm 980 can besubstantially flush with a distal edge of the protrusion 991 of the arm990 in the illustrated orientation. Likewise, a distal edge of the tip999 of the arm 990 can be substantially flush with a distal edge of theprotrusion 981 of the arm 980. Thus, it can be seen that the protrusions981 and 991 together limit the amount of initial penetration that ispossible when the device 1000 is applied against tissue in theillustrated orientation (e.g. in the retracted or undeployed state).

In the illustrated embodiment, the distal edges of the tip 979 and theprotrusion 981 of the arm 980 are at approximately the same axialposition at or near a distal end 1007 of the tube 1005. Similarly, thedistal edges of the tip 999 and the protrusion 991 of the arm 990 are atapproximately the same axial position. In the illustrated embodiment,these edges are substantially flush with the distal surface 1007 of thetube 1005. Such an arrangement can further control a manner and/or anamount of a tissue layer that can be received into a gap 1009 or tissuereceiving region. This can also control a manner in which portion of thetissue layer that is received therein is engaged as the arms 980, 990are deployed (FIGS. 35B-35E).

As previously mentioned, FIG. 35D shows the arms 980, 990 in their fullyactuated positions and prior to the deployment of the puncture needle102. The device 1000 can include an actuation rod 1010 that can effectdeployment of the arms 980, 990 in manners such as described above. Theactuation rod 1010 can define a channel or lumen 1012 within which theneedle 1002 is carried. In the illustrated embodiment, the actuation rod1010 can be advanced distally independent of the needle 1002. Once theactuation rod 1010 has completed deployment of the arms 980, 990, theneedle 1002 can be advanced distally through the channel 1012. Theneedle 1002 can be advanced beyond the distal end of the actuation rod1010, as shown in FIG. 35F.

In some instances the protrusions 981, 991 can be advantageous in stagessuch as that depicted in FIG. 35D. In such circumstances, the additionalmaterial of protrusions 981 and 991 can enhance the ability to see theactuated arms with imaging methods such as fluoroscopy, which arecommonly used during procedures for which the device 1000 is wellsuited. Yet another advantage is that the protrusions can act as safetyguards by shielding the tip points (e.g. tip 979 of arm 980). Forexample, if the device is withdrawn while the arms are inadvertentlyactuated, the protrusions will minimize unintended tissue trauma bydiverting tissue away and around the tips 979, 999 during retraction ofthe device 1000. In some instances, the protrusions 981, 991 couldassist in or even effectuate partial or full retraction of the arms insuch situations, as drawing the protrusions 981, 991 proximally pasttissue could force them to rotate partially or fully into the retractedstate.

In some instance, the ability to rapidly retract the needle during theprocedure—after delivery of the guidewire, for example—may be desired bythe user. FIG. 36 depicts an example of a rapid retraction mechanism,adapted to the threaded coupling between the needle assembly 950 and thedevice handle 902. Here, handle threads 940 are located on a slideablesegment 945 which can be displaced inwardly by applying a pinching forcealong direction 946. During normal use, internal springs (not visible)apply an outward biasing force that maintains engagement between handlethreads 940 and dial threads 960. Thus, needle assembly 950 can bequickly disengaged and removed by applying the pinching force alongdirection 946 and retracting assembly 950. Additionally a biasingelement, such as a coil spring, may be inserted between needle assembly950 and handle 902 such that needle assembly 950 is urged away duringretraction.

Referring to FIG. 37, another accessory feature for assisting with userhandling of the device is described. FIG. 37 illustrates a slideable andlockable collar 961 that fits over tube 903. Means for locking collar961 to tube 903 include friction, collets, clamping or other commonmeans for fixing an object axially mounting on a shaft. In someinstances, after a user has successfully actuated engagement arms (inthis embodiment 980 and 990), and applied traction to the soft tissue,the user may wish to maintain such traction while performing furthersteps, such as insertion of the guidewire. Rather than manually holdingsuch traction, collar 961 may be slid distally along tube 903 until itis against the patient's skin. Then collar 961 may be locked in positionagainst the skin. This will maintain the traction on the soft tissue,and frees the user's hand for performing subsequent steps of aprocedure.

In the embodiment shown in FIG. 37, the shaft 903 of device 901 slidesinto lockable collar 961. However, lockable collar 961 may have anopening along its length so that it can be slipped onto the shaft 903 ofdevice 901 and taken off without having to slide the device throughlockable collar 961. This can be advantageous if, for example, thelockable collar 961 is to be removed while the device 901 is inserted ina patient.

Embodiments have been described herein in the context of pericardialaccess, but discussion of this context should not be considered limitingas other uses and applications are contemplated. For example, someembodiments are used in endoscopic third ventriculostomy (ETV), whichrequires lifting the floor of the third ventricle from the underlyingtissue to be able to create a hole through it. Another exemplaryapplication is in laparascopic access into the peritoneal space thatrequires pulling tissue layers, such as peritoneum, from underlyingtissue layers or organs. The device and techniques disclosed herein canbe further used in various other applications and procedures.

Advantageously, embodiments described herein have features, geometry,and structure that allow the tissue engagement devices to be massproduced cost effectively. Preferred manufacturing methods for the maincomponents include metal stamping, plastic molding, machining, and lasercutting. Other manufacturing methods known to those of ordinary skill inthe art are also contemplated.

The present invention has now been described with reference to severalillustrative embodiments thereof. The foregoing disclosure has beenprovided for clarity of understanding by those skilled in the art. Nounnecessary limitations should be taken from the foregoing disclosure.It will be apparent to those skilled in the art that changes can be madein the illustrative embodiments described herein without departing fromthe scope of the present invention. Thus, the scope of the presentinvention should not be limited to the illustrative structures andmethods described herein, but only by the structures and methodsdescribed by the language of the claims and the equivalents of thoseclaimed structures and methods.

Any methods disclosed herein comprise one or more steps or actions forperforming the described method. The method steps and/or actions may beinterchanged with one another. In other words, unless a specific orderof steps or actions is required for proper operation of the embodiment,the order and/or use of specific steps and/or actions may be modified.

References to approximations are made throughout this specification,such as by use of the terms “about” or “approximately.” For each suchreference, it is to be understood that, in some embodiments, the value,feature, or characteristic may be specified without approximation. Forexample, where qualifiers such as “about,” “substantially,” and“generally” are used, these terms include within their scope thequalified words in the absence of their qualifiers. For example, wherethe term “substantially flush” is recited with respect to a feature, itis understood that in further embodiments, the feature can have aprecisely flush orientation.

Any reference throughout this specification to “certain embodiments” orthe like means that a particular feature, structure or characteristicdescribed in connection with that embodiment is included in at least oneembodiment. Thus, the quoted phrases, or variations thereof, as recitedthroughout this specification are not necessarily all referring to thesame embodiment or embodiments.

Similarly, it should be appreciated that in the above description ofembodiments, various features are sometimes grouped together in a singleembodiment, figure, or description thereof for the purpose ofstreamlining the disclosure. This method of disclosure, however, is notto be interpreted as reflecting an intention that any claim require morefeatures than those expressly recited in that claim. Rather, as thefollowing claims reflect, inventive aspects lie in a combination offewer than all features of any single foregoing disclosed embodiment.

The claims following this written disclosure are hereby expresslyincorporated into the present written disclosure, with each claimstanding on its own as a separate embodiment. This disclosure includesall permutations of the independent claims with their dependent claims.

Recitation in the claims of the term “first” with respect to a featureor element does not necessarily imply the existence of a second oradditional such feature or element. Elements specifically recited inmeans-plus-function format, if any, are intended to be construed inaccordance with 35 U.S.C. § 112(f). Embodiments of the invention inwhich an exclusive property or privilege is claimed are defined asfollows.

1. A tissue engagement device comprising: a tube that defines a lumenhaving a maximum interior width; an actuation rod positioned within thelumen of the tube; a plurality of arms, each arm comprising a piercingtip; and an actuator configured to move the actuation rod relative tothe tube to rotate the arms between (i) a retracted orientation in whichthe tips of adjacent arms are at a distance from each other that is lessthan the maximum interior width of the lumen and (ii) an actuatedorientation in which the tips of adjacent arms are directed away fromeach other and are spaced from each other by a distance that is greaterthan the maximum interior width, wherein, when a distal end of thetissue engagement device abuts a layer of tissue, actuation of the armsvia the actuator rotates the tips into the layer of tissue to pierce thelayer of tissue and to apply tension to the layer of tissue outwardly inopposite directions, and wherein the piercing tips of the arms arepositioned distally beyond a distal face of the tube when the arms arein the retracted orientation.
 2. The tissue engagement device of claim1, wherein the tips of the arms face away from each other when thetissue engagement device is in the retracted orientation.
 3. The tissueengagement device of claim 1, wherein the actuation rod comprises a tipat a distal end thereof, and wherein the piercing tips of the armsextend distally past the distal tip of the actuation rod during at leasta portion of a transition of the arms from the retracted orientation tothe actuated orientation.
 4. The tissue engagement device of claim 1,wherein the piercing tips of the arms extend distally past the distalface of the tube during at least a portion of a transition of the armsfrom the retracted orientation to the actuated orientation.
 5. Thetissue engagement device of claim 1, wherein at least a portion of eacharm is positioned distally relative to the distal face of the tubethroughout a transition of the arms from the retracted orientation tothe actuated orientation.
 6. The tissue engagement device of claim 1,wherein the arms are pivotally coupled either to the tube or to theactuation rod.
 7. The tissue engagement device of claim 1, furthercomprising a puncture needle that comprises a tip configured to puncturethrough a tissue layer after the tissue layer has been engaged by thearms.
 8. The tissue engagement device of claim 7, wherein the actuationrod defines a needle pathway through which the puncture needle passes.9. The tissue engagement device of claim 8, wherein the needle pathwayis either parallel to or collinear with a central axis of the tube. 10.The tissue engagement device of claim 8, wherein the needle pathwayextends between the arms.
 11. The tissue engagement device of claim 7,further comprising a fitting attached to the proximal end of thepuncture needle, the fitting comprising a Luer connection interface. 12.The tissue engagement device of claim 1, wherein the actuator comprisesa lever, a knob, or a sliding button.
 13. The tissue engagement deviceof claim 1, wherein the actuation rod is moved distally relative to thetube to transition the arms from the retracted orientation to theactuated orientation.
 14. The tissue engagement device of claim 1,wherein the piercing tips of the arms are configured to embed within orotherwise engage the pericardium of a heart without passing through thepericardium of the heart when the arms are transitioned from theretracted orientation to the actuated orientation.
 15. The tissueengagement device of claim 1, wherein the piercing tips of the arms areconfigured to move only in transverse and proximal directions relativeto the tube when the arms are transitioned from the retractedorientation to the actuated orientation.
 16. The tissue engagementdevice of claim 1, wherein the piercing tips of the arms move in unisonwith each other along oppositely directed paths as the arms aretransitioned from the retracted orientation to the actuated orientation.17. The tissue engagement device of claim 1, wherein the piercing tipsof the arms are at the distal end of the tissue engagement device whenthe arms are in the retracted orientation.
 18. The tissue engagementdevice of claim 1, wherein the actuation rod comprises a tip at thedistal end of the tissue engagement device, wherein the tip of theactuation rod is recessed relative to the distal face of the tube whenthe arms are in the retracted orientation.
 19. The tissue engagementdevice of claim 1, wherein the piercing tips of the arms are eachsharpened along one or more bevel planes.
 20. A tissue engagement devicecomprising: a tube that defines a lumen having a maximum interior width;an actuation rod configured to be positioned within the lumen of thetube, the actuation rod defining a needle pathway; a plurality of arms,each arm comprising a piercing tip; an actuator configured to move theactuation rod relative to the tube to transition the arms between (i) aretracted orientation in which the tips of adjacent arms are at adistance from each other that is less than the maximum interior width ofthe lumen and (ii) an actuated orientation in which the tips of adjacentarms are directed away from each other and are spaced from each other bya distance that is greater than the maximum interior width; and a needleconfigured to pass through the needle pathway of the actuation rod whilethe arms are in the actuated orientation, wherein, when a distal end ofthe tissue engagement device abuts a layer of tissue, actuation of thearms via the actuator introduces the tips into the layer of tissue toengage the layer of tissue and to apply tension to the layer of tissueoutwardly in opposite directions, wherein, proximal movement of thetissue engagement device when the arms are in the actuated orientationand engage the layer of tissue causes the layer of tissue to lift awayfrom underlying tissue, and wherein the needle pathway is oriented todirect a distal end of the needle to puncture through the layer oftissue as the needle is advanced distally through the needle pathwaywhile the layer of tissue remains lifted away from the underlyingtissue.
 21. The tissue engagement device of claim 20, wherein the needlepathway is collinear with a central axis of the tube.
 22. The tissueengagement device of claim 20, wherein the needle pathway extendsbetween the arms when the arms are in the actuated orientation.
 23. Atissue engagement device comprising: a tube that defines a lumen havinga maximum interior width; an actuation rod configured to be positionedwithin the lumen of the tube, the actuation rod defining a needlepathway; a plurality of arms, each arm comprising a piercing tip; anactuator configured to move the actuation rod relative to the tube totransition the arms between (i) a retracted orientation in which thetips of adjacent arms are at a distance from each other that is lessthan the maximum interior width of the lumen and (ii) an actuatedorientation in which the tips of adjacent arms are directed away fromeach other and are spaced from each other by a distance that is greaterthan the maximum interior width; and a needle configured to pass throughthe needle pathway of the actuation rod, wherein the needle pathwayextends between the arms when the arms are in the actuated orientation.24. The tissue engagement device of claim 23, wherein the needle pathwayextends between the arms when the arms are in the retracted orientation.